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| Fontanier, Christophe; Garnier, Eline; Brandily, Christophe; Dennielou, Bernard; Bichon, S.; Gayet, Nicolas; Eugene, Thibaut; Rovere, Mickael; Gremare, A.; Deflandre, B.. |
| Live (Rose-Bengal stained) deep-sea foraminiferal faunas have been studied at four stations between 530–3200-m depth in the Mozambique Channel (eastern Africa) to understand how complex environmental conditions (e.g., organic matter, oxygenation) control their ecological structure (i.e., diversity, density, and microhabitats). Two upper-slope stations, located at 530- and 780-m depth off Madagascar, are bathed by well-oxygenated bottom waters. They are characterized by fine sediments enriched in highly degraded organic matter (low amino-acid bio-availability and reduced chlorophyllic freshness). Mineralization of organic compounds results in relatively moderate oxygen penetration depth (i.e., 15 and 30 mm) in sediment. Interestingly, foraminiferal species... |
| Tipo: Text |
Palavras-chave: Mozambique Channel; Foraminifera; Diversity; Microhabitat; Organic matter. |
| Ano: 2016 |
URL: http://archimer.ifremer.fr/doc/00344/45505/45057.pdf |
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| Pastor, L.; Cathalot, C.; Deflandre, B.; Viollier, E.; Soetaert, K.; Meysman, F. J. R.; Ulses, C.; Metzger, E.; Rabouille, C.. |
| In situ oxygen microprofiles, sediment organic carbon content, and pore-water concentrations of nitrate, ammonium, iron, manganese, and sulfides obtained in sediments from the Rhone River prodelta and its adjacent continental shelf were used to constrain a numerical diagenetic model. Results showed that (1) the organic matter from the Rhone River is composed of a fraction of fresh material associated to high first-order degradation rate constants (11-33 yr(-1)); (2) the burial efficiency (burial/input ratio) in the Rh boolean AND one prodelta (within 3 km of the river outlet) can be up to 80 %, and decreases to similar to 20% on the adjacent continental shelf 10-15 km further offshore; (3) there is a large contribution of anoxic processes to total... |
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| Ano: 2011 |
URL: https://archimer.ifremer.fr/doc/00303/41423/40614.pdf |
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| Cathalot, C.; Rabouille, C.; Pastor, L.; Deflandre, B.; Viollier, E.; Buscail, R.; Treignier, C.; Pruski, A.. |
| The biogeochemical fate of the particulate organic inputs from the Rhône River was studied on a seasonal basis by measuring sediment oxygen uptake rates in the prodelta, both during normal and flood regimes. On a selected set of 10 stations in the prodelta and nearby continental shelf, in situ and laboratory measurements of sediment oxygen demand were performed in early spring and summer 2007 and late spring and winter 2008. In and ex situ sediment Diffusive Oxygen Uptakes (DOU) did not show any significant differences except for shallowest organic rich stations. DOU rates show highest values concentrated close to the river mouth (approx. 20 mmol O2 m-2 d-1) and decrease offshore to values around 4.5 mmol O2 m-2 d-1 preferentially in a south west... |
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| Ano: 2009 |
URL: https://archimer.ifremer.fr/doc/00303/41428/40611.pdf |
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| Cathalot, C.; Rabouille, C.; Pastor, L.; Deflandre, B.; Viollier, E.; Buscail, R.; Gremare, A.; Treignier, C.; Pruski, A.. |
| River deltas are particularly important in the marine carbon cycle as they represent the transition between terrestrial and marine carbon: linked to major burial zones, they are reprocessing zones where large carbon fluxes can be mineralized. In order to estimate this mineralization, sediment oxygen uptake rates were measured in continental shelf sediments and river prodelta over different seasons near the outlet of the Rhone River in the Mediterranean Sea. On a selected set of 10 stations in the river prodelta and nearby continental shelf, in situ diffusive oxygen uptake (DOU) and laboratory total oxygen uptake (TOU) measurements were performed in early spring and summer 2007 and late spring and winter 2008. In and ex situ DOU did not show any significant... |
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| Ano: 2010 |
URL: https://archimer.ifremer.fr/doc/00303/41427/40610.pdf |
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| Pastor, Lucie; Rabouille, C.; Metzger, E.; De Chanvalon, A. Thibault; Viollier, E.; Deflandre, B.. |
| Floods carry sediments to river deltas and the coastal zone, but little is known about the geochemical evolution of this particulate material deposited over a short period of time. Here, we studied two recent contrasting flood deposits in the Rhône River prodelta area (northwestern Mediterranean Sea). We monitored the porewater and solid-phase chemistry over periods ranging from a few days to 6 months after deposition. Non-steady state diagenetic processes associated with episodic deposition promote a wide spectrum of transient redox conditions in the shallow prodelta region of the Rhône. Specific attributes of diagenetic responses depend on the sources of flood material and scale (thickness) of deposition. The first flood unit of 20–30 cm was composed of... |
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| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00449/56049/57568.pdf |
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